The present invention relates to an impact energy absorption member used to absorb impact energy to prevent the damage of transportation equipment by absorbing impact energy generated in the collision thereof, the transportation equipment including vehicles such as a passenger car, a track, and the like, airplanes such as a passenger plane and the like, vessels such as a fishing boat, a ferry boat, and the like, railroad cars such as an electric car, a monorail car, and the like.
Transportation equipment such as vehicles, motor cars, and the like which has a possibility of collision while it moves is provided with an impact energy absorption mechanism for protecting an equipment main body and the life of crews from the impact generated in the collision. A hollow metal frame, a polymer-formed material, and so on, for example, have been used as a conventional impact energy absorption member.
Incidentally, a mechanism in which the conventional impact energy absorption member absorbs energy is such that a metal- or polymer-formed material receives an impact force, is deformed by compression or bending, and absorbs impact energy through the subsequent plastic deformation or breakage thereof.
For example, Japanese Unexamined Patent Application Publication No. 9-2178 proposes an impact absorption structure for the interior member of motor cars for absorbing impact by that a rib portion is pressed and deformed by being bent. The publication exhibits characteristics such as an elastic modulus in bending, Izod strength, and the like.
Further, Japanese Unexamined Patent Application Publication No. 9-95197 proposes an energy absorption structure for the side portion of a vehicle body capable of effectively absorbing energy in such a manner that a rib portion is elastically deformed and a load sequentially increases accordingly. The publication further describes a shape having a hollow portion.
Furthermore, Japanese Unexamined Patent Application Publication No. 5-32147 proposes an impact energy absorption member for a bumper using a fiber-reinforced composite material. The mechanism of the composite material is such that when the material is deformed by compression, it is exfoliated and broken so that energy to be absorbed thereby increases.
However, since the conventional impact energy absorption members utilize plastic deformation and breakage due to compression as described above, the wall thickness of a member cannot help being increased, that is, the member cannot help being formed in a bulky shape such as a hollow shape together with an increased wall thickness in order to absorb a large amount of energy which is generated in collision at a high speed. Thus, these conventional impact energy absorption members are disadvantageous in that the space of a cabin of transportation equipment is reduced and the dwelling property thereof is scarified and further the overall weight of the impact energy absorption members increases and gas mileage is lowered, which is undesirable from an economical and environmental viewpoint.
In contrast, the transportation equipment is required to greatly reduce its weight from the view point of administration for protecting environment. It is expected to apply a sophisticated composite material, that is, a fiber-reinforced composite material (hereinafter, abbreviated as FRP) that seems to greatly reduce a weight and to improve durability as a material to be replaced with a metal material. However, the FRP is a material that does not almost exhibit plastic deformation and has compression and bending strength which is almost the same as that of the metal material while the FRP has tensile strength that is larger than that of the metal material. Therefore, it is difficult to actually use the FRP at present because the FRP does not have a sufficient merit in the reduction of weight in the conventional impact energy absorbing mechanism which is broken in the compression and bending modes.
Accordingly, a first object of the present invention is to provide a light and compact impact energy absorption member that makes use of the aforementioned bending and compression modes and can eliminate the drawbacks of the conventional heavy and bulky impact energy absorption member for transportation equipment and sufficiently absorb impact energy from a moving body in the occurrence of collision.
In particular, it is an urgent matter to establish compatibility between safety against collision from various directions and reduction in weight of an impact energy absorbing apparatus from the special circumstances in which motor vehicles for personal use occupy almost all the portion of the transportation equipment. Thus, a second object of the present invention is to provide a means for solving the above problem.
An impact energy absorption member of the present invention is characterized by comprising a long member of fiber reinforced resin having a lengthwise direction and a thickness direction, wherein the ratio(t/L) of the thickness t (mm) of the long member to the length L (mm) thereof is within the range of 1/11000 to 6/1000 as well as the direction of an external force is substantially in agreement with the thickness direction of the impact member.
When the impact energy absorption member of the present invention is used, it is jointed and fixed mechanically and/or through bonding to portions where the member is desired to absorb impact energy such as the insides of a door and a bumper, the inner surface and the external surface of a side panel, the rear portion of an engine, the periphery of a cabin for crews, and the like.